Multitech MT64DSU Owner's Manual page 19

Switch #7
Data Set Ready "DSR"
(Asynchronous/Synchronous Mode)
When this option is enabled, the MultiDSU64K forces the DSR
signal on continuously. The continuous DSR signal is used to
eliminate momentary link interruptions that may be interpreted by
the DTE as a communications channel failure.
DSR controlled by DSU
DSR Forced On
(Factory Default Setting
Switch #8
Local Loopback Test (to DTE)
Refer to Diagnostics Tests section in Chapter 4.
Switch #9
Digital Loopback Test (to the Line)
Refer to Diagnostics Tests section in Chapter 4.
Switch #10
Remote Digital Loopback Test
Refer to Diagnostics Tests section in Chapter 4.
Switch #11
Test Pattern
Refer to Diagnostics Tests section in Chapter 4.
Switch #12
Elastic Store
(Asynchronous/Synchronous Mode)
This function allows the MultiDSU64K to compensate for small
timing phase "drifts" that occur in applications using analog modems
for off-net (non-DDS) extensions. An analog off-net extension
application is described in Appendix A. This option should be
enabled on all MultiDSU64Ks that are connected to analog
modems.
Chapter 2 - Installation and Connection
= Switch #7 UP
= Switch #7 DOWN
= DOWN)
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